| 摘要 |
<p>PURPOSE:To shorten a required time for the operation of a clutch and to smoothly make a engagement-operation thereof without generating any shock by changing a preset current value for a preset time in order to control an electromagnetic proportional pressure-reducing valve when the engagement-operation of the clutch for changing speed. CONSTITUTION:An electromagnetic proportional pressure-reducing valve V and a forward/backward switching valve 21 are provided in an oil passage 20 from a hydraulic pump 19 to a clutch C. The electromagnetic proportional pressure-reducing valve V is controlled by a current regulating means 18 every time the the forward/backward switching valve 21 is operated. The current regulating means 18 outputs the first current value for a period of the first preset time from the time of the operation of the forward/backward switching valve 21, and outputs the second current value which is smaller than the first current value for a period of the second preset time, and after the second preset time passes, the third current value which is increased as the time passes is output. Accordingly, the piston is operated in high speed until the state of a half-clutch appears so as to shorten the required time of the operation, thus the hydraulic clutch can be smoothly engaged without generating any shock.</p> |
